(1) Field of the Invention
The present invention relates to a cooling unit mounting structure for a flat display, and a plasma television set employing the cooling unit mounting structure for the flat display.
(2) Description of Related Art
Television sets displaying broadcast image on a display have long been popular in families as a key media on which we watch amusement programs, movies, news or the like. The size of a screen of the television set has been increased with improvement in living standards. However, CRT-based television sets which have long been predominant have problems in a depth, weight or dissipation power because of the structure thereof. An increase in the size of a cathode ray tube sees the end coming.
On the other hand, display devices such as plasma television sets and liquid crystal displays which quite differ from the cathode ray tube have recently been developed as the result of improvements in the electronic, semiconductor or material technique. These display devices are thinner as compared with the conventional cathode ray tube. Accordingly, television sets provided with these display devices are generally referred to as flat-screen television sets.
The flat-screen television sets have realized lower costs and larger size together with progress in the technical development and volume efficiency. The flat-screen television sets have now replaced the conventional cathode ray tube system and enlarged its market because of demand due to replacement with transition from terrestrial broadcasting to digital and in consistent with housing conditions in Japan.
When a television employing the above-described flat display is manufactured, general-purpose panel components supplied by a panel manufacturer are sometimes assembled together into a panel assembly, to which a unique control processing technique and the like are added. In such assembling of general-purpose panel components, the panel components, a filter and a resin-molded cabinet are generally assembled together.
FIG. 6 shows a conventional assembling structure in the case where a flat display is a plasma display panel. A plasma display panel 1 is attached to a rear of a standing generally frame-like panel holder 2 with spacers 3 being mounted on four corners of the panel holder rear. The plasma display panel 1 is fixed to the panel holder 2 by screws at one side of the latter. The spacers 3 are provided in order that the plasma display panel 1 is spaced from a filter 4 as will be described later.
On the other hand, the filter 4 is attached to a front of the panel holder 2 with a gasket 5 being interposed therebetween. Upper, lower, right and left sides of the filter 4 are engaged with four film holders 6 each of which is a linear frame having a step with a crank-shaped section. The filter 4 is then fixed by screws at the front of the panel holder 2. A generally frame-like cabinet 7 is attached to the panel holder 2 with the filter 4 at the front side of the panel holder 2. A bezel 8 is then attached to the cabinet 7 so as to cover a gap between the cabinet 7 and a view-area outer periphery. The cabinet 7 and the bezel 8 are fixed by screws at rear of the panel holder 2.
Two parallel chassis brackets 9 are mounted on the upper and lower frame portions of the panel holder 2 so as to be located at the rear side of the plasma display panel 1. A control board, an input/output device and the like are mounted on the chassis brackets 9. Thus the chassis brackets 9 structurally serve as backbones.
In the assembling of the plasma display panel 1, the panel holder 2, plasma display panel 1, filter 4, cabinet 7, chassis brackets 9 and the like are assembled together while these components are standing.
Since high voltage is applied to the plasma display panel 1, a large amount of heat is generated from the plasma display panel 1, the control board mounted on the rear of the plasma display panel 1 and the like during operation of the plasma display panel 1. Moreover, a rear cabinet (not shown) is mounted around the plasma display panel 1 so as to be close to the same, whereupon a closed space is defined in which heat tends to remain.
A fan is provided for cooling an interior atmosphere by sucking and discharging heated air in the interior space in order that an increase in the interior temperature due to the above-described heat generation may be restrained for stable operation. For example, two cooling fans 9a are mounted using a dedicated fan holder 9b so as to be located between the plasma display panel 1 and the rear cabinet and so as to slightly be displaced upward so that the cooling fans are prevented from overlap with the control board.
The fan holder 9b is generally plate-shaped as shown in FIG. 7. The fan holder 9b extends between the two parallel chassis brackets 9 and horizontally screwed so that the cooling fans 9a are spaced at the rear side of the plasma display panel 1.
The fan holder 9b has two through holes at predetermined locations respectively. The cooling fans 9a are screwed in the through holes respectively. The rear cabinet has slits provided for air discharge and opposed to the cooling fans 9a respectively.
Air remaining in a closed space defined between the plasma display panel 1 and the rear cabinet is discharged outside through the slits of the rear cabinet. Consequently, the closed space is maintained at or above a predetermined temperature so that a stable operation of the plasma display can be ensured.
However, the above-described cooling fan mounting structure has the following problems. More specifically, as described above, when television sets employing a flat display such as the plasma display panel 1 are manufactured, general purpose components supplied from a panel manufacturer are assembled together, and a unique control processing technique and the like are added to the panel assembly in many cases. In this case, when a plurality of panel manufacturers are involved, specifications of the display panels such as configurations, dimensions of the display panels differ between or among the panel manufacturers. Accordingly, a plurality of fan holders 9b having different configurations need to be prepared according to the different specifications of the fan holders 9b. This results in cost increases.
In the above-described assembly of the plasma display panel 1, the components such as the panel holder 2, plasma display panel 1, filter 4, cabinet 7 and chassis brackets 9 are assembled together while these components are standing. Accordingly, while holding the fan holder 9b by one hand, a work needs to fasten the screws so that the fan holder can be prevented from falling and screw holes are correctly aligned. Thus, the working efficiency is low.
Furthermore, hot air tends to rise upward and accordingly, hot air in a lower area of the closed space relative to the mounting locations of the cooling fans 9a is discharged more efficiently. However, hot air in an upper area of the closed space relative to the mounting locations of the cooling fans 9a tends to remain in the area. A cooling fan with a higher discharge performance needs to be provided so that a sufficient air discharge is carried out, resulting in increases in costs, noise and electric power consumption.
Furthermore, the components such as the control board, input/output device and the like are mounted on each chassis bracket 9 as described above. These components become obstacles when the cooling fans 9a are mounted at locations suitable for air discharge. As a result, a sufficient cooling performance cannot be achieved or a depth of the plasma display panel is increased.
On the other hand, the conventional art provides the following mounting structures for a cooling fan mounted in electronic equipment.
More specifically, in JP-A-H08-228086, a mounting structure is described in which a holder has an open end from which engagement pieces and a positioning part extend and slits and screw holes are provided. A cooling fan is housed in the holder, and an engagement portion, a positioning protrusion, an engagement claw and screw hole are provided in a peripheral edge of a discharge hole of the equipment housing so as to correspond to the slits and screw holes. The cooling fan is mounted on the housing with a holder being interposed therebetween. According to the above structure, the mounting work can easily be carried out.
In JP-A-2005-197421, a fan is housed in a fan box formed with a hook engagement portion. A hook corresponding to the hook engagement portion is provided on a rear panel of the equipment. A fan is mounted on the rear panel with the fan box being interposed therebetween. According to the above structure, the mounting work can easily be carried out, too.
In JP-A-2003-173147, a board mounted on the rear of a display panel with gaps from upper and lower reinforcing ribs. A discharge space is ensured for cooling air flowing from the gaps. According to the above structure, cooling can reliably be carried out.
In JP-A-H08-228086, when a cooling fan is mounted, the mounting work can be simplified as compared with a simple mounting structure using screws. JP-A-2005-197421 fan holders having different configurations need to be prepared accordingly. The problem of cost increases cannot be overcome.
Furthermore, the problem of discharge of hot air in the upper space relative to the mounting position of the cooling fan cannot be overcome, either.
In the structure described in JP-A-2005-197421, the cooling fan is mounted with interposition of the fan box as in the description of JP-A-H08-228086. As a result, the mounting work can be rendered easier as compared with the mounting structure employing the screws. In this structure, however, when a plurality of panel manufacturers are involved, fan boxes with different configurations need to be prepared. The problem of cost increases cannot be overcome.
Furthermore, the problem of discharge of hot air in the upper space relative to the mounting position of the cooling fan cannot be overcome, either.
In the structure described in JP-A-2003-173147, the problem of discharge of hot air in the upper space relative to the mounting position of the cooling fan cannot be overcome although a hot air discharging efficiency can be improved.
Furthermore, JP-A-2003-173147 cannot overcome the problems that the specifications such as the configuration, dimension and the like of the panel holder and the problem of the mounting efficiency cannot be overcome.